Continuous rolling mill drive



April 21, 1964 G. HERGETH 3,129,618

CONTINUOUS ROLLING MILL DRIVE Filed May 23, 1961 3 Sheets-Sheet 1 ROLL STAND SPEED llllllll 1 2 3 4 5 6 7 8 9 IO N l2 REDUCING STANDS SPEED OF ROLL TO OF REDUCTION Muen/or Ger/20rd Herge/h By his af/omeys PASS=H= 2 Al April 21, 1964 G. HERGETH I 3,129,618

CONTINUOUS ROLLING MILL DRIVE Filed May 23; 1961 s SheeQs-Sheet 2 PASSjk 3 i y I PASS April 21, 1964 HERGETH 3,129,618

CONTINUOUS ROLLING MILL DRIVE Filed May 23, 1961 3 Sheets-Sheet 3 QL 4 F/G. 7

mven 20/ V Ger/20m Herge/h By Ms al/omeys United States Patent" 3,129,618 CONTINUOUS ROLLING MILL DRIVE Gerhard Hergeth, Monchen-Gladbach, Germany, assignor to h Iannesmann-Meer Ahtiengesellschaft, Monchen- Gladbaeh, Germany, a corporation of German Filed May 23, 1961, Ser. No. 111,954 2 Claims. (Cl. 80-35) Tln's invention is for a continuous multi-stand rolling mill drive and more particularly one for a mill having two or more roll stands. The normal continuous rolling mill is driven by a constant speed drive and is limited in the range of product sizes it can turn out. It has been known to provide a multi-stand rolling mill with a variable speed drive to overcome this handicap but the cost of this equipment is large and it is the object of the present invention to make a drive which approximates the capabilites of a variable speed drive reducing mill in the variety of product sizes it can produce without the high initial capital investment required for a variable speed drive. According to the present invention the product size range of a normal constant speed mill drive is increased and the operation of a stretch reducing mill is approximated without the cost of a variable speed drive. The new arrangement has the advantage that a rolling mill can easily be changed over from one speed range, i.e. product size, to another where hitherto two different rolling mills were required. To accomplish this two difierent positive speed drives are provided for each stand arranged symmetrically about the mill pass center line and the elements are so arranged that when one positive drive is connected to the mill stand the other is always idle. To shift from one drive to the other it is only necessary to pull a mill stand out of contact with its active drive, turn the stand upside down and push it back into its new operating position. The stand is thereby connected by gears to its other drive with its different speed. Yet the product range can be doubled for a negligible cost.

In the drawings FIGURE 1 is a perspective view of a mill stand ready to be meshed with a lower drive according to the invention by pushing the stand in the direction of the straight arrow, the curled arrow showing the direction of rotation of the shaft of the driven roll and indicative of the mill pass direction.

FIGURE 2 is a view similar to FIGURE 1 of a mill stand turned upside down preparatory to meshing with the upper drive the arrows indicating as before.

FIGURE 3 is a graph showing the speed of the roll stands compared to the percent of reduction of size of the material for each of the two drives or conditions at each roll stand for a twelve stand mill.

FIGURE 4 is a simplified line diagram showing the alternate plugging in of six of the stands to their upper and lower drives to produce the speed or condition 1 of FIGURE 3.

FIGURE 5 is a line diagram similar to FIGURE 4 showing the plugging in of six of the stands to produce the speed or condition 2 of FIGURE 3.

FIGURE 6 is a plan view taken on the section line 6-6 of FIGURE 7 and a similar section line of FIG- URE 8 of the first four roll stands of the six passes of FIGURE 4, showing the connections of the stands to the constant speed mill drive shaft, the inactive gears in the gear transfer case being shown in dotted lines and the symbol on each mill stand casing suggesting the positions of the rolls in that stand viewed in elevation analogous to FIGURES 1 and 2.

FIGURE 7 is a simplified view in elevation across the mill of FIGURE 6 looking at the second, fourth or sixth stand connected as in FIGURE 2, looking in the direction in which the product moves, the view being taken on the line 7-7 of FIGURE 6.

3,129,618 Patented Apr. 21, 1964 FIGURE 8 is a View in elevation similar to FIGURE 7 showing the first, third or fifth mill stand connected to its lower drive spindle, the view being taken on the line 7-7 of FIGURE 6.

In a plain reducing mill the relationship of the roll speeds from one roll stand to the next is determined by the constant speed drive. As mentioned, the object of the invention is to introduce flexibility into the operation of such a conventional mill so it can handle a larger variety of product sizes while still driven by a constant speed drive and also to approximate the operation of a stretch reducing mill without the high initial capital investment required for a variable speed drive. It will be noted that the invention can be either in a solid drive transmission or a variable speed transmission.

In the drawings is shown sufiicient of a preferred form of twelve stand mill drive made in accordance with the invention to illustrate the nature thereof. The drive has a. frame 1 and a plurality of removable mill stands indicated generally by the reference numeral 2. There is an input or main drill drive shaft 3 adapted to provide power to all the mill stands. This connects to the mill stands 2 through a transfer gear case 4 and a clamping frame 19 that will be described later. Protruding from the gear case through the frame opposite each mill stand are an upper spindle 5 and a lower spindle 6, each with internal gear teeth 7. These can each be a slip connection coupling. A mill stand 2 is connected to one of these spindles by a mill stand drive coupling 3 with external gear teeth 9. These teeth mesh with the internal teeth 7 on the drive spindle 5 or 6 providing a positive drive connection between the transfer gear case 4 and the mill stand 2. The mill stands shown each contain three rolls 10 located at angles apart. As usual only one roll per stand is driven directly, this roll being connected to the mill stand drive coupling 8 above referred to. The other two are geared to the first mentioned roll in the stand. Each mill stand 2 is on a carriage 11 on a track 12. By being retracted along the track, a stand can be disengaged from both the gear case spindles 5, 6 or moved forward to bring the mill stand spindle into mesh with one of the gear case spindles.

In order to hold the mill stands in their working positions the main frame of the mill has a mill center line clamping frame 19 curving up and over the mill stands as shown in FIGURES 7 and 8. There is an hydraulic stand clamp 20 in the clamping frame. It is suggested in FIGURES 7 and 8. Each clamp holds its stand in the operating position. The driving spindles 5, 6 for the stands pass through the clamping frame 19 and are supported by it. A detachable friction clutch 21 can be provided on each spindle between the transfer gear case 4 and the frame 19 (see FIGURES 6, 7 and 8).

In the embodiment of FIGURES 6, 7 and 8 the main drive shaft 3 for the mill drives the mill stands by the following elements. The main drive shaft 3 need not be at the level of the center line of the mill pass. Opposite each mill stand there are two bevel gears 13, one on the main drive shaft 3 and the other meshing with it on a stub shaft 14. The latter shaft 14 connects via a friction clutch 22 with the transfer gear case by a gear case drive shaft 23. This is connected by gears 2%, 30 to a center shaft 24 which we have shown in FIGURES 7 and 8 on the center line of the mill pass. From this center shaft 24 the drives for upper and lower mill stand drive spindles 5 and 6 separate. By means of gear 25 on the shaft 24 and a gear 26 on the upper spindle 5 power can be transmitted to the upper spindle. Analogously another gear 27 on the center shaft 24 meshes with a gear 28 on the lower spindle 6 whereby power goes to the lower spindle. The upper and lower spindles 5, 6 are shown in FIGURES 7 and 8 symmetrically arranged on opposite sides of the center line of the mill pass and this is true of the arrangement of the drives for the two types of stands in these figures. These spindles are each in two pieces separated by a friction clutch 21.

On the simplified line diagrams of FIGURES 4 and 5 the gears for driving the successive stands are shown on opposite sides of the mill pass center line to emphasize the fact that the upper and lower drive spindles 5, 6 are driven at different speeds. It is essential, however, that the spindles be symmetrically arranged about the mill pass center line. There is the gear case drive shaft 14, the small gear 15 and the large gear 16 both driven from the drive shaft 14. By meshing the spindles 5, 6 having small gears 15, the speed arrangement line 18 of FIG- URE 5 giving the roll stand speed condition 2 of FIG- URE 5 is produced. If the speed arrangement line 17 of condition 1 of FIGURE 4 is to be produced the small gears 15 are in operation.

The gears at successive stands produce gradually increasing speeds as usual compared to the main or input drive shaft of the mill drive because of the increased length of the tube due to the gradual reduction in diameter and the change of wall thickness of the tube as the rolling progresses.

Assuming a twelve stand reducing mill making pipe a typical reduction in pipe size obtained is shown as part of FIGURE 3. Starting with 3 /2 inch pipe, passage through the condition 1 would reduce the pipe to 2% inches. If each mill stand were now turned upside down so that it would be driven through the small gears 15 and the speed line arrangement 18 'of FEGURE 5, condition 2 would result and a two inch pipe would be brought down to a dimension of, say, 1.050 inches. This is a larger reduction than condition 1. It will be seen that in this way one mill can handle double the size range heretofore possible. Also it has done so with positive drives throughout and with out the expense of a variable speed drive.

It will be obvious that if desired the gears, etc. can be used to give stretch reducing, i.e. where there is a change in wall thickness of the tube.

It might be noted that the alternate arrangement of successive mill stands where every second three roll stand is inverted, i.e. turned 180 and connected to an upper drive, has been heretofore known but the provision of special gearing to so combine this as to make two speed ranges possible is new.

In reducing mills it has been kown to alternate adjacent stands in orientation about the axis of the Work. This is done because the rolls protrude on each side beyond the framework of the roll stand which supports them. The effectiveness of reduction from stand to stand is greater when the stands are closer together and when the stands are driven alternately from top and bottom drives with the inversion. In this way the rolls of adjacent stands fit into the spaces between the rolls at each side, rather than having the rolls in opposition and it is possible to bring the stands closer together. It also ensures that each stand rolls the work in areas not effectively rolled at the previous stand, this area being the point of tangency of the rolls.

The spindles 5 and 6 act as shafts driven positively from the main input shaft 3 of the entire mill by the means shown. They are so geared by these means that each spindle drives its stand at a different speed than the other spindle of the pair of spindles for the stand, this being over and above the increasing rate or sequence from stand to stand to offset the efifects at each successive stand on the product.

What is claimed is:

1. Continuous rolling mill apparatus permitting change from one speed range to another comprising a frame, a plurality of stands in said frame individually removable therefrom, the stands being arranged to provide a common mill pass center line, a common input drive shaft for said stands, and two spindles on the frame driven from the common input drive shaft of each stand, one to drive its stand when one side up and the other to drive the stand when turned 180, in combination with gears associated with each drive spindle in each stand providing a different speed range compared to the other spindle; whereby the mill can cover an increased range of speeds merely by turning the stands 180".

2. Continuous rolling mill. apparatus permitting change from one speed range to another comprising a frame, a

plurality of stands in said frame individually removable therefrom, a spindle on each stand from which the same can be driven and a common input drive shaft for the stand, in combination with two spindles on the frame driven from the common input drive shaft, one to drive the stand when one side thereof is up and the other to drive the stand when turned 180, and gears associated with each frame spindle determining the speed of drive obtained from that spindle, the gears for the two spindles in any stand providing a speed of drive different from each other and the gears for one spindle of each of the successive stands providing a different speed range from the gears for the other spindles in successive stands; whereby the speed range covered by the mill can be changed merely by turning the stands 180.

Great Britain Sept. 14, 1960 Germany Oct. 9, 1958 

1. CONTINUOUS ROLLING MILL APPARATUS PERMITTING CHANGE FROM ONE SPEED RANGE TO ANOTHER COMPRISING A FRAME, A PLURALITY OF STANDS IN SAID FRAME INDIVIDUALLY REMOVABLE THEREFROM, THE STANDS BEING ARRANGED TO PROVIDE A COMMON MILL PASS CENTER LINE, A COMMON INPUT DRIVE SHAFT FOR SAID STANDS, AND TWO SPINDLES ON THE FRAME DRIVEN FROM THE COMMON INPUT DRIVE SHAFT OF EACH STAND, ONE TO DRIVE ITS STAND WHEN ONE SIDE UP AND THE OTHER TO DRIVE THE STAND WHEN TURNED 180*, IN COMBINATION WITH GEARS ASSOCIATED WITH EACH DRIVE SPINDLE IN EACH STAND PROVIDING A DIFFERENT SPEED RANGE COMPARED TO THE OTHER SPINDLE; WHEREBY THE MILL CAN COVER AN INCREASED RANGE OF SPEEDS MERELY BY TURNING THE STANDS 180* 